1. Field of the Invention
The present invention relates to a damper disc used in a lock-up clutch of automotive torque converter or the like, and more particularly to the improvement of the structure for holding the damper spring in such damper disc.
2. Description of the Prior Art
In the Japanese Utility Model Application 61-170593 by the present applicant, a damper disc similar to the present invention is disclosed. Such damper disc comprises an input plate (piston) mounting an abrasion facing for input, an output plate fixed to turbine (turbine shell or turbine hub), and a damper spring (coil spring) for coupling the two plates, and also a holding plate for supporting the spring is provided.
This holding plate is fixed to the input plate, and a linkage part (pawl) linking in the circumferential direction is provided at the end portion of the spring. Therefore, the input plate is coupled to the spring by way of the holding plate. The holding plate is also designed to hold the spring in the radial direction, and accordingly it comprises a tubular inside support part stretching along the inner circumference of the spring, and a tubular outside support part stretching along the outer circumference of the spring. Furthermore, there is also an outside part on the outer circumference of the input plate.
According to this structure, when the spring is about to move in the operating state outward in the radial direction by the centrifugal force, the spring is supported by this outside support part to arrest such movement, so that the specified action may be effected securely by stabilizing the position of the spring. In this operation, moreover, since the outer circumference of the outside support part is supported by the outer end of the input plate, extreme deformation of the outside support part in the radial direction by the centrifugal force from the spring may be prevented.
However, since the support plate is treated for hardening, the stiffness is high, and the input plate is also high in stiffness, and therefore it is difficult to assemble the holding plate into the input plate by elastically deforming the both plates in the assembling process. As a result, considering the dimensional errors of the both plates, in the assembling process, it is necessary to set the outside diameter of the support part smaller than, if very slightly, than the outer end of the input plate in order to fit the outside support part of the holding plate into the outer end of the input plate. Accordingly, a slight gap is formed between the support part and the tubular part, and when the support part receives the centrifugal force from the spring as mentioned above, the support part is deformed outward in the radial direction by the portion of this gap, so that a crack may be formed in the holding plate.
The invention is intended to present a structure capable of solving the above problems.